Incandescent lamp



May 13, 1930.

A. D. DE CASTRO INCANDES CENT LAMP Filed. June 14, 1926 IN VEN TOR. mm? vemfi ATTORNEYS.

Patented May 13, 1930 ADOLPHE D. DE CASTRO, OF NEW YORK, N. Y.

INCANDESCENT LAMP Application filed June 14,

This invention relates to improvements in electric incandescent lamps and has for 1ts object to provide a multiple filament lamp and thermo-electrically controlled means responsive to temporary or permanent interruption in the operation of one filament for automatically connecting the other filament with the source of current supply and ma1ntaining it in circuit throughout its period of operativeness.

A further object is the provision of a thermally controlled multiple filament lamp embodying a thermo-sensitive device of such improved structure that it may be economically manufactured and compactly reduced to such dimensions that it may be readily assembled within the incandescent lamp.

In the accompanying drawing wherein an approved embodiment of the invention is il-' lustrated.

Fig. 1 is a side elevation, partly in section of the improved lamp.

Figs. 2 and 3 are diagrammatic views illustrating the two positions of the thermosensitive device.

Referring to the drawing in detail, 5 indicates the usual incandescent lamp bulb provided with a base portion 6 enclosed in the usual metallic cap 7 having external screw threads to adapt it for insertion in the usual lamp socket. The bulb 5 is provided internally with a filament support 8 carrying filament supporting arms 9 supporting two independent filaments 10 and 11 which are preferably of substantially annular form as suggested in Figs. 2 and 3 with the object of improving the illuminating efficiency of the 1am O iie terminal each of the two filaments 10 and 11 are connected by conductors 12 and 13 to the conductor 14 extending upwardly through the filament support 8 and connected at 15 with the metallic cap or shell 7. The opposite ends of the filaments 10 and 11 are connected by conductors .16 and 17, re- .spectively to the two relativel stationary contact members 18 and 19 whic in the embodiment of the invention illustrated, are embedded in the walls of a cavity 20 formed 50 in the filament support 8.

1926. Serial No. 115,976.

The thermo-sensitive circuit controlling device is received within the cavity 20 and includes a thermo-sensitive element 21 of the bi-metallic or other type, one end of which is anchored in the bulb base 6 as indicated at 22. The thermo-sensitive element 22 is of such form that under normal thermal conditions, it lies in contact with the contact member 19 as illustrated in Fig. 2 and, when heated, it is flexed as indicated in Fig. 3 but still remains in engagement with the contact member 19. The thermo-sensitive element 21 is formed of conducting material and is electrically connected by a conductor 23 with the center electrode 24 of the lamp, thus at all times the center electrode 24 is electrically connected with one end' of the filament 11 through the conductor 23, thermo-sensitive element 21, contact member 19 and conductor 17. A spring contact member 25 is secured to the element 21 adjacent its anchored end and it is so arranged as to engage the contact member 18 under normal thermal conditions.

The initial position of the thermally controlled device is illustrated in Figs. 1 and 2 in which the circuit to both filaments 10 and 11 is closed through the contact members 18 and 19 and the spring 25 and element 21, respectively. .When the lamp is connected with a source of current both filaments are caused to light but only momentarily because the passage of currentthrough the thermosensitive element 21 heats the latter and causes it to occupy the position shown in Fig. 3. With the thermo-sensitive device in this position the spring 25 is disengaged from the contact member 18 and the passage of current to the filament 10 is interrupted at this point. The filament 11 is maintained in an incandescent condition throughout the period that current is supplied thereto and the element 21 is also maintained in the flexed condition shown in Fig. 2.

When the filament 11 is rendered inoperative due to breakage or forv any other reason, the passage of current through the major portion of the element 21 is interrupted and upon cooling sufliciently it resumes the position shown in Fig. 2 whercupon the current passes from the center electrode 24 through the conductor 23, anchored portion of the element 21, spring 25, contact member 18, conductor 16, filament 10 and then to the conductor 14 common to both filaments.

What I claim is 1. In an incandescent lamp, a plurality of filaments, a conductor common to one terminal of each filament, a continuous circuit from said terminal to the other terminal of one of said filaments including a thermo responsive element in said lamp, a make-andbreakv contact device in circuit with the other of said filaments, and one of the elements of the make-and-break contact device being secured to the thermo responsive element.

2. In an incandescent lamp having two filaments, a conductor common to one terminal of each filament, a continuous circuit from said terminal to the otherterminal of one of the filaments including a thermo responsive element in said lamp, a make-andbreak contact device'in vcircuit with the other one of the filaments, said thermo responsive contact element maintaining a continuous circuit through one of saidfilaments and designed to open the make-and-brcak contact to the otherfilament, whereupon the opening of the circuit including the thermo responsive element, the make-and-break contact device will make contact, closing the circuit of the other of said filaments.

In testimon whereof I aflix my si nature.

AD LPHE D. DE CAST O. 

